The ENEA Laser Application Section has participated to the European project ISOTREX (Integrated system for on-line
trace explosives detection in solid and vapor state), funded in the frame of the PASR 2006 with the main aim to exploit
different laser based techniques. Standard explosive compounds and their precursors have been investigated through an
atomic technique (LIBS; Laser-Induced Breakdown Spectroscopy), an absorption technique (LPAS; Laser Photoacoustic
Spectroscopy) and vibrational techniques (Laser Raman and SERS; Surface-Enhanced Raman Spectroscopy). LIBS and
SERS reached a sub ng level of detection, supported by a high rank of discrimination of the components via
chemometric analysis. This selectivity skill is also quite evident in the LPAS technique. These results assume particular
relevance due to the inclusion of interferents, such as dust, fingerprint oil and lubricant oil, into the investigated
compounds. The results of the measurements are presented in view of the possible integration of the three techniques in a
single device for trace detection, might contribute also to drastically limit the number of false positives.
The reactive oxygen species (ROS) produced inside cells by UV-B radiation may induce apoptosis, a process that
realizes the programmed death of cells. In the present paper the UV induced damage was studied in a human T-Lymphocyte
cell line (the Jurkat line) by mean of IR laser photoacoustic spectroscopy (PAS) and by Fourier Transform
Infrared Spectroscopy (FTIR) combined with biological assays based on flow cytometry. The apoptosis was induced in
vitro in the Jurkat samples by exposition to UV-B radiation with a dose of 310 mJ/cm2. PAS measurements were
performed through a 10W c.w. CO2 laser based optical system realised at ENEA Molecular Spectroscopy Laboratory in
A laser sensor realised at ENEA Frascati (Italy) based on photoacoustic spectroscopy (PAS), able to detect gas
concentrations down to sub-ppb level, was applied for revealing ethylene traces emitted in the exhaled breath by human
subjects, before as well as after an antioxidant treatment. In the present work, the changes in breath ethylene detected by
PAS, compared to a direct analysis of reactive oxygen species detected in the blood by a spectrophotometric method (d-
ROMs), were investigated in each patient. The sensorial system, the methods, the experiment and the results are
discussed in the paper.
The emission of ethylene from climacteric fruit banana (Musa x paradisiaca L.) and non climacteric fruits lemon (Citrus limon Burm. F.) at different stages of ripening (from a few days after setting to full maturity stage) by the Laser Photoacoustic Spectroscopy System, developed in ENEA Frascati, was measured. A high ethylene production rate from mature banana fruit was found, as expected for climacteric fruit. Significant differences between ethylene emitted by the lemon after setting stage and by the young fruit were observed. Also ethylene emission from lemon fruits at different ripening stages (from light green to turning and full ripe) was detected. Depending on the ripening stage, differences in ethylene emission rates were found, although the emissions were low as expected for non-climacteric fruit.
The paper underlines the importance of breath tests in medicine and the potential of laser techniques to measure in-vivo and in real time human biomarkers. The presence of trace amounts of gases or the metabolites of a precursor in exhaled air could be linked to kidney or liver malfunction, asthma, diabetes, cancer, ulcers or neurological disorders. The measurement of some human biomarkers (ethylene, ammonia), based on laser photoacoustic spectroscopy methods, insure very high sensitivity and selectivity. The technical characteristics of this instrument were measured to determine the detection limits (sub-ppb for ethylene). The results of ethylene release following lipid peroxidation initiated by X-ray irradiation or ingestion of radioactive compounds are presented. The possibility to extend this technique for measurement of breath ammonia levels in patients with end-stage renal disease while they are undergoing hemodialysis is discussed.
In the experiments reported in this paper small traces of ethylene down to ppb level have been detected by means of photoacoustic spectroscopy in the breath exhaled from humans. The method has been applied in studying how the concentration of the ethylene coming out from human lungs is modified after smoking. We followed up the evolution of ethylene concentration in the case of several people by monitoring the ethylene before and after smoking. In each case the first exhaled air sample was collected prior smoking the cigarette and compared with the samples collected after 30 minutes following the inhalation of cigarette smoke. In all the experiments a high value of ethylene concentration was found immediately after smoking. The experimental laser based photoacoustic system has been realized in ENEA Laboratories in Frascati, Italy.
We demonstrate fabrication of 2D photonic crystal structure inside the volume of SU-8 resist by four beams interference. This structure, actually, is a 3D structure fabricated inside the film without sample scanning laser beam steering. The mechanism of recording in transparent dielectrics is discussed in terms of third harmonic generation, white light continuum, and thermal emission by "hot" electrons.
A laser based photoacoustic system has been designed and built at ENEA in order to monitor bio-gases produced in different processes involving living cells. Experiments aimed to reveal traces of ethylene emitted from tomato plantlets and fruits under temperature stress are here presented and discussed.
IMany trace gases can be found in the exhaled breath, some of them giving the possibility of a non invasive diagnosis of related diseases or allowing the monitoring of the disease in the course of its therapy. In the present lecture the principle of medical diagnosis based on the breath analysis will be introduced and the detection of trace gases in exhaled breath by high- resolution molecular spectroscopy in the IR spectral region will be discussed. A number of substrates and the optical systems for their laser detection will be reported. The following laser based experimental systems has been realised in the Molecular Spectroscopy Laboratory in ENEA in Frascati for the analysis of specific substances in the exhaled breath. A tuneable diode laser absorption spectroscopy (TDLAS) appartus for the measurement of 13C/12C isotopic ratio in carbon dioxide, a TDLAS apparatus for the detection of CH4 and a CO2 laser based photoacoustic system to detect trace ethylene at atmospheric pressure. The experimental set-up for each one of the a.m. optical systems will be shown and the related medical applications will be illustrated. The concluding remarks will be focuses on chemical species that are of major interest for medical people today and their diagnostic ability.
In this paper thyroid samples have been analyzed by fluorescent technique and characterization of the spectral response has been performed by studying both emission and excitation fluorescence spectra. The measurements have been performed by using a double monochromator spectrofluorometer. The nature of the medium containing the tissue sample has resulted to be of great importance in eliminating spurious effects not related to the sample itself. Observations fulfilled on a number of samples will be reported and comparison between healthy tissue and tumor tissue will be discussed.
Infrared absorption spectroscopy can be performed at very high resolution by tunable diode laser (TDL) based optical systems for any gas with well resolved absorption spectra. In a double beam setup atmospheric trace gas concentration can be measured down to ppb levels. The analysis of trace gases may have useful applications in detecting chemicals in the human breath for non invasive medical diagnostic. The capability of TDL based breath analysis was well demonstrated by monitoring ammonia and methane. In the human body the formation of free radicals does induce oxidative degradation of polyunsaturated fatty acids (lipid peroxidation) which is a damage for cells and organs in the organism. Specific volatile hydrocarbons generated as end product by lipid peroxidation (LP) can be found inside circulating blood and expired breath. TDL based analysis of those specific hydrocarbons (ethane and pentane) in the expired breath can allow a non invasive assessment of the LP extent.